Bridging Earth and Space: A Survey on HAPS for Non-Terrestrial Networks

TL;DR

This survey explores the role of High Altitude Platform Stations (HAPS) in 6G networks, highlighting their potential to connect terrestrial and space-based systems with advanced technologies and addressing current research challenges.

Contribution

It provides a comprehensive overview of HAPS technologies, use cases, integration strategies, and recent advancements, filling gaps in existing literature on their role in 6G.

Findings

HAPS enable wide-area coverage and low-latency communications.

Recent field trials demonstrate practical deployment potential.

Key technologies include AI-driven resource management and energy efficiency.

Abstract

HAPS are emerging as key enablers in the evolution of 6G wireless networks, bridging terrestrial and non-terrestrial infrastructures. Operating in the stratosphere, HAPS can provide wide-area coverage, low-latency, energy-efficient broadband communications with flexible deployment options for diverse applications. This survey delivers a comprehensive overview of HAPS use cases, technologies, and integration strategies within the 6G ecosystem. The roles of HAPS in extending connectivity to underserved regions, supporting dynamic backhauling, enabling massive IoT, and delivering reliable low-latency communications for autonomous and immersive services are discussed. The paper reviews state-of-the-art architectures for terrestrial and non-terrestrial network integration, highlights recent field trials. Furthermore, key enabling technologies such as channel modeling, AI-driven resource allocation, interference control, mobility management, and energy-efficient communications are examined. The paper also outlines open research challenges. By addressing existing gaps in the literature, this survey positions HAPS as a foundational component of globally integrated, resilient, and sustainable 6G networks.